The use of implanted Deep Brain Stimulation (DBS) for the treatment
of the symptoms of Parkinson's disease has been the focus of a lot
of research activity and technological innovation over recent
years. Last week, St. Jude Medical announced positive results from a
controlled study of their Libra family of DBS implantable pulse generators, the results of which were published in the journal The Lancet Neurology.

The objective of the study was to evaluate the safety and
effectiveness of the Libra devices in managing the symptoms of
Parkinson's disease. The study was carried out on on 136 Parkinson's
patients in 15 clinical sites throughout the U.S. and the primary
endpoint was an increase in the duration in which patients had good
control of their symptoms and motor functions.

Both study groups reported a mean increase of good
quality on time after three months, and the increase was greater in the
stimulation group (4·27 h vs 1·77 h, difference 2·51 [95% CI
0·87--4·16]; p=0·003). Unified Parkinson's disease rating scale motor
scores in the off-medication, on-stimulation condition improved by 39 percent
from baseline (24·8 vs 40·8). Some serious adverse events
occurred after DBS implantation, including infections in five (four percent) of
136 patients and intracranial haemorrhage in four (three percent) patients.
Stimulation of the subthalamic nucleus was associated with dysarthria,
fatigue, paraesthesias, and oedema, whereas gait problems,
disequilibrium, dyskinesia, and falls were reported in both groups.

The Libra devices used in this study are essentially constant current
pulse generators which deliver a fixed current 'dose' irrespective of
changes in the properties of the region being stimulated. According to
the company website the devices are currently available in Europe, Latin America, and Australia for managing the symptoms of PD.